Reinhold Buck - Academia.edu (original) (raw)
Papers by Reinhold Buck
Contributions To Nephrology, Apr 16, 2015
Progress in membrane and membrane process development have contributed to the continuous improvem... more Progress in membrane and membrane process development have contributed to the continuous improvement of the extracorporeal treatment of renal failure during the last 40 years. Today membranes can be adapted to the specific needs required by their clinical application. Synthetic structures like the polyamide membranes offer a wide range of possibilities in performance and hemocompatibility, due to: (1) the use of block polymers or polymer blends and mixtures, and (2) modification of membrane structure, pore size and porosity, due to changes of the preparation process. However, further improvements are still required to achieve the ultimate goal of matching the performance of biological membranes.
Progress in membrane and membrane process development have contributed to the continuous improvem... more Progress in membrane and membrane process development have contributed to the continuous improvement of the extracorporeal treatment of renal failure during the last 40 years. Today membranes can be adapted to the specific needs required by their clinical application. Synthetic structures like the polyamide membranes offer a wide range of possibilities in performance and hemocompatibility, due to: (1) the use of block polymers or polymer blends and mixtures, and (2) modification of membrane structure, pore size and porosity, due to changes of the preparation process. However, further improvements are still required to achieve the ultimate goal of matching the performance of biological membranes.
PURPOSE: To obtain an improved selectively permeable asymmetric membrane as a laminated three lay... more PURPOSE: To obtain an improved selectively permeable asymmetric membrane as a laminated three layer structure consisting of a first layer of a dense thin coating film having a screening function, a second layer with a sponge structure having a highly diffusive permeability and serves as a supporting body and a third layer with a finger-like structure which provides the membrane with mechanical stability. CONSTITUTION: Hydrophobic polymers such as polyamide are dissolved in a soln. in which hydrophilic polymers such as polyvinyl pyrolidone(PVP) and an additive such as water are dissolved into dimethyl sulfoxide(DMSO) or the like. These polymers are extruded out of an external annular slit of a nozzle having two coaxial openings, and simultaneously, principal liqs. (nonsolvents against hydrophobic polymers) such as the solns. of the DMSO, PVP and water are extruded out of an internal opening. Obtd. hollow fibers are washed with water, and thereafter, are glycerinated and dried. The ob...
Membrane hollow asymmetric fiber, and selective permeability, which is suitable for, for example,... more Membrane hollow asymmetric fiber, and selective permeability, which is suitable for, for example, hemodialysis, comprised of at least one hydrophobic polymer which is polyethersulphone or a mix of polyarylethersulphone and polyamide, and at least one hydrophilic polymer is polyvinylpyrrolidone characterized in that said membrane has a four layer structure comprising a first inner layer separation in the form of a dense rather thin layer, a second layer in the form of a sponge structure, a third layer in form of a finger structure, and a fourth outer layer in form of a sponge layer having an outer surface with pores in the range of 0.5 to 3 microns, and wherein the number of said pores on the outer surface is in the range of 10,000 to 150,000 pores per mm2, preferably in the range of 18,000 to 100,000 pores per mm2 and, most preferably in the range of between 20,000 and 100,000 po ros per mm2.
Asymmetric hollow fiber membrane and selective permeability for the separation of toxic mediators... more Asymmetric hollow fiber membrane and selective permeability for the separation of toxic mediators from blood, comprised of at least one hydrophobic polymer and at least one innermost of hydrophilic polymer, in which is present a separation layer in the layer hollow fiber characterized in that said membrane allows passage of molecules having a molecular weight up to 45,000 Daltons with sieving coefficient of between 0.1 and 1.0 in presence of whole blood, and has a value of nominal cut 200,000 Daltons with a sieving coefficient 0.1, in water.
La presente invention concerne un procede continu pour la preparation de membranes en fibres creu... more La presente invention concerne un procede continu pour la preparation de membranes en fibres creuses a permeabilite selective, etant appropriee, par exemple, pour l'hemodialyse, l'hemodiafiltration et l'hemofiltration de sang, lequel comprend un sechage en deux etapes et un traitement de trempe des membranes en fibres creuses. Selon un aspect supplementaire, l'invention concerne un procede continu pour le sechage de membranes en fibres creuses a permeabilite selective en ligne. L'invention concerne egalement des dispositifs pour le sechage en ligne de membranes en fibres creuses a permeabilite selective.
A SYMMETRICAL MEMBRANE WITH ADEQUATE SELECTIVE PERMEABILITY IS PRESENTED FOR HEMODIALYSIS, HEMODI... more A SYMMETRICAL MEMBRANE WITH ADEQUATE SELECTIVE PERMEABILITY IS PRESENTED FOR HEMODIALYSIS, HEMODIAFILTRATION AND HEMOFILTRATION OF THE BLOOD CONSISTING OF A FIRST HYDROPHOBIC POLYMER, A SECOND HYDROPHOBIC POLYMER AND SUITABLE ADDITIVES. THE MEMBRANE IS CHARACTERIZED BY A THREE-LAYER STRUCTURE THAT INCLUDES A FIRST LAYER IN THE FORM OF PRETTY FINE SKIN, WHICH IS RESPONSIBLE FOR SIZING PROPERTIES, A SECOND LAYER IN THE FORM OF A SPONGEOUS STRUCTURE, WHICH HAS A HIGH PERMEABILITY AND THAT IS AS A SUPPORT FOR SUCH A FIRST LAYER AND A THIRD LAYER IN THE FORM OF A SUPPORT STRUCTURE THAT GIVES THE MEMBRANE A MECHANICAL STABILITY. A PROCESS FOR THE MANUFACTURING OF THE MEMBRANE IS ALSO DESCRIBED.
A method for preparing by solvent phase inversion spinning a hollow fiber membrane suitable for d... more A method for preparing by solvent phase inversion spinning a hollow fiber membrane suitable for dialysis. The membrane includes at least one hydrophobic polymer and at least one hydrophilic polymer. An outer surface of the membrane is characterized by pores having sizes in the range of 0.5-3 mum, with the density of the pores on the outer surface of the membrane being in the range of 10,000 to 150,000 pores per mm2. The method includes dissolving the at least one hydrophobic polymer and the at least one hydrophilic polymer in at least one solvent to form a polymer solution, extruding the thus-formed polymer solution through an outer ring slit of a nozzle with two concentric openings, extruding a center fluid through the inner opening of the nozzle, and wishing said membrane. The polymer solution coming out through the outer slit opening on the outside of the precipitating fiber is exposed to a humid steam/air mixture including a solvent content of between 0.5 and 10% by weight relat...
NEW DEVICE FOR PROCEDURES NEEDING PERMANENT ACCESS TO BLOOD CIRCULATION Bosticardo Gian Mario. Ne... more NEW DEVICE FOR PROCEDURES NEEDING PERMANENT ACCESS TO BLOOD CIRCULATION Bosticardo Gian Mario. Nephrology, Ospedale degli Infermi, Biella, IT. The new vascular access rationale is derived from limits of central venous catheters (CVC), arterial venous fistula (AVF) and grafts (AVG). PVAS is based on mechanical lock concept, and has four components: soft graft, obturator, tunnel and protective sheaths. Graft dimensions, established by Poiseuille formula, are lenght 80mm, inner diameter 4mm; it is bifurcated at the distal extremity, the inner extremity uncovered to allow sweet curve to native vessel. Outer extremity and bifurcation are reinforced by a titanium rigid sheath, stabbed by dacron cuff. The obturator is protected to guarantee sterility, several solutions considered: “accordion sheath” (figure 1), “foldable sheath” and “balloon obturator”. Major advantage of PVAS on CVC is implant on peripheral vessels, that saving central veins might avoid life threatening complications. As ...
Background Membrane based medical therapies have increased considerably in recent years. However,... more Background Membrane based medical therapies have increased considerably in recent years. However, very few changes have focused on the structure and components of the dialyzer. Consequently, the “current high flux dialyzers” are very much the same as they were 20 years ago. The need for more efficient dialyzers is clear. The necessity to mass produce these new dialyzers at a low cost has also placed demands on any membrane used in medical applications today. These demands are for specific transport characteristics, high clearances, blood compatibility and a design that enables a costefficient and reliable method of production. Objective To assess performance, thrombogenicity, blood and dialysate flow characteristics and ease of use, an in vitro and in vivo study program was conducted with the Polyflux Revaclear and Polyflux Revaclear MAX dialyzers —next-generation high-flux dialyzers with advanced membrane composition and design characteristics. Results The Polyflux Revaclear dialyz...
Contributions To Nephrology, Apr 16, 2015
Progress in membrane and membrane process development have contributed to the continuous improvem... more Progress in membrane and membrane process development have contributed to the continuous improvement of the extracorporeal treatment of renal failure during the last 40 years. Today membranes can be adapted to the specific needs required by their clinical application. Synthetic structures like the polyamide membranes offer a wide range of possibilities in performance and hemocompatibility, due to: (1) the use of block polymers or polymer blends and mixtures, and (2) modification of membrane structure, pore size and porosity, due to changes of the preparation process. However, further improvements are still required to achieve the ultimate goal of matching the performance of biological membranes.
Progress in membrane and membrane process development have contributed to the continuous improvem... more Progress in membrane and membrane process development have contributed to the continuous improvement of the extracorporeal treatment of renal failure during the last 40 years. Today membranes can be adapted to the specific needs required by their clinical application. Synthetic structures like the polyamide membranes offer a wide range of possibilities in performance and hemocompatibility, due to: (1) the use of block polymers or polymer blends and mixtures, and (2) modification of membrane structure, pore size and porosity, due to changes of the preparation process. However, further improvements are still required to achieve the ultimate goal of matching the performance of biological membranes.
PURPOSE: To obtain an improved selectively permeable asymmetric membrane as a laminated three lay... more PURPOSE: To obtain an improved selectively permeable asymmetric membrane as a laminated three layer structure consisting of a first layer of a dense thin coating film having a screening function, a second layer with a sponge structure having a highly diffusive permeability and serves as a supporting body and a third layer with a finger-like structure which provides the membrane with mechanical stability. CONSTITUTION: Hydrophobic polymers such as polyamide are dissolved in a soln. in which hydrophilic polymers such as polyvinyl pyrolidone(PVP) and an additive such as water are dissolved into dimethyl sulfoxide(DMSO) or the like. These polymers are extruded out of an external annular slit of a nozzle having two coaxial openings, and simultaneously, principal liqs. (nonsolvents against hydrophobic polymers) such as the solns. of the DMSO, PVP and water are extruded out of an internal opening. Obtd. hollow fibers are washed with water, and thereafter, are glycerinated and dried. The ob...
Membrane hollow asymmetric fiber, and selective permeability, which is suitable for, for example,... more Membrane hollow asymmetric fiber, and selective permeability, which is suitable for, for example, hemodialysis, comprised of at least one hydrophobic polymer which is polyethersulphone or a mix of polyarylethersulphone and polyamide, and at least one hydrophilic polymer is polyvinylpyrrolidone characterized in that said membrane has a four layer structure comprising a first inner layer separation in the form of a dense rather thin layer, a second layer in the form of a sponge structure, a third layer in form of a finger structure, and a fourth outer layer in form of a sponge layer having an outer surface with pores in the range of 0.5 to 3 microns, and wherein the number of said pores on the outer surface is in the range of 10,000 to 150,000 pores per mm2, preferably in the range of 18,000 to 100,000 pores per mm2 and, most preferably in the range of between 20,000 and 100,000 po ros per mm2.
Asymmetric hollow fiber membrane and selective permeability for the separation of toxic mediators... more Asymmetric hollow fiber membrane and selective permeability for the separation of toxic mediators from blood, comprised of at least one hydrophobic polymer and at least one innermost of hydrophilic polymer, in which is present a separation layer in the layer hollow fiber characterized in that said membrane allows passage of molecules having a molecular weight up to 45,000 Daltons with sieving coefficient of between 0.1 and 1.0 in presence of whole blood, and has a value of nominal cut 200,000 Daltons with a sieving coefficient 0.1, in water.
La presente invention concerne un procede continu pour la preparation de membranes en fibres creu... more La presente invention concerne un procede continu pour la preparation de membranes en fibres creuses a permeabilite selective, etant appropriee, par exemple, pour l'hemodialyse, l'hemodiafiltration et l'hemofiltration de sang, lequel comprend un sechage en deux etapes et un traitement de trempe des membranes en fibres creuses. Selon un aspect supplementaire, l'invention concerne un procede continu pour le sechage de membranes en fibres creuses a permeabilite selective en ligne. L'invention concerne egalement des dispositifs pour le sechage en ligne de membranes en fibres creuses a permeabilite selective.
A SYMMETRICAL MEMBRANE WITH ADEQUATE SELECTIVE PERMEABILITY IS PRESENTED FOR HEMODIALYSIS, HEMODI... more A SYMMETRICAL MEMBRANE WITH ADEQUATE SELECTIVE PERMEABILITY IS PRESENTED FOR HEMODIALYSIS, HEMODIAFILTRATION AND HEMOFILTRATION OF THE BLOOD CONSISTING OF A FIRST HYDROPHOBIC POLYMER, A SECOND HYDROPHOBIC POLYMER AND SUITABLE ADDITIVES. THE MEMBRANE IS CHARACTERIZED BY A THREE-LAYER STRUCTURE THAT INCLUDES A FIRST LAYER IN THE FORM OF PRETTY FINE SKIN, WHICH IS RESPONSIBLE FOR SIZING PROPERTIES, A SECOND LAYER IN THE FORM OF A SPONGEOUS STRUCTURE, WHICH HAS A HIGH PERMEABILITY AND THAT IS AS A SUPPORT FOR SUCH A FIRST LAYER AND A THIRD LAYER IN THE FORM OF A SUPPORT STRUCTURE THAT GIVES THE MEMBRANE A MECHANICAL STABILITY. A PROCESS FOR THE MANUFACTURING OF THE MEMBRANE IS ALSO DESCRIBED.
A method for preparing by solvent phase inversion spinning a hollow fiber membrane suitable for d... more A method for preparing by solvent phase inversion spinning a hollow fiber membrane suitable for dialysis. The membrane includes at least one hydrophobic polymer and at least one hydrophilic polymer. An outer surface of the membrane is characterized by pores having sizes in the range of 0.5-3 mum, with the density of the pores on the outer surface of the membrane being in the range of 10,000 to 150,000 pores per mm2. The method includes dissolving the at least one hydrophobic polymer and the at least one hydrophilic polymer in at least one solvent to form a polymer solution, extruding the thus-formed polymer solution through an outer ring slit of a nozzle with two concentric openings, extruding a center fluid through the inner opening of the nozzle, and wishing said membrane. The polymer solution coming out through the outer slit opening on the outside of the precipitating fiber is exposed to a humid steam/air mixture including a solvent content of between 0.5 and 10% by weight relat...
NEW DEVICE FOR PROCEDURES NEEDING PERMANENT ACCESS TO BLOOD CIRCULATION Bosticardo Gian Mario. Ne... more NEW DEVICE FOR PROCEDURES NEEDING PERMANENT ACCESS TO BLOOD CIRCULATION Bosticardo Gian Mario. Nephrology, Ospedale degli Infermi, Biella, IT. The new vascular access rationale is derived from limits of central venous catheters (CVC), arterial venous fistula (AVF) and grafts (AVG). PVAS is based on mechanical lock concept, and has four components: soft graft, obturator, tunnel and protective sheaths. Graft dimensions, established by Poiseuille formula, are lenght 80mm, inner diameter 4mm; it is bifurcated at the distal extremity, the inner extremity uncovered to allow sweet curve to native vessel. Outer extremity and bifurcation are reinforced by a titanium rigid sheath, stabbed by dacron cuff. The obturator is protected to guarantee sterility, several solutions considered: “accordion sheath” (figure 1), “foldable sheath” and “balloon obturator”. Major advantage of PVAS on CVC is implant on peripheral vessels, that saving central veins might avoid life threatening complications. As ...
Background Membrane based medical therapies have increased considerably in recent years. However,... more Background Membrane based medical therapies have increased considerably in recent years. However, very few changes have focused on the structure and components of the dialyzer. Consequently, the “current high flux dialyzers” are very much the same as they were 20 years ago. The need for more efficient dialyzers is clear. The necessity to mass produce these new dialyzers at a low cost has also placed demands on any membrane used in medical applications today. These demands are for specific transport characteristics, high clearances, blood compatibility and a design that enables a costefficient and reliable method of production. Objective To assess performance, thrombogenicity, blood and dialysate flow characteristics and ease of use, an in vitro and in vivo study program was conducted with the Polyflux Revaclear and Polyflux Revaclear MAX dialyzers —next-generation high-flux dialyzers with advanced membrane composition and design characteristics. Results The Polyflux Revaclear dialyz...